pho·tom·e·ter 
(fō-tŏmĭ-tər)
(fō-tŏmĭ-tər)n.
An instrument for measuring a property of light, especially luminous intensity or flux.
- fractionation
- fractionator
- fractionization
- fractionize
- fractious
- fractiously
- fractiousness
- fracture
- frae
- frag
- fragger
- fragile
- fragilely
- fragileness
- fragile X syndrome
- fragility
- fragment
- fragmental
- fragmentally
- fragmentarily
- fragmentariness
- fragmentary
- fragmentation
- fragmentation bomb
- fragmentation grenade